1. Field of the Invention
The present invention relates to a burner which is low in the generation of nitrogen oxides, used in a small combustion apparatus for domestic or commercial use.
2. Description of the Background
The nitrogen oxides (NO.sub.x) in the exhaust gases from burners of various combustion apparatuses, are themselves toxic and are believed to cause acid rain and photochemical smog. So, for burners used in combustion apparatuses, various measures for decreasing the generation of NO.sub.x have been developed and utilized.
However, these measures are mainly taken for legally regulated, large combustion apparatuses for industrial use and other services, and it cannot be said that satisfactory measures are being taken for small combustion apparatuses for domestic or commercial use, especially with respect to the noise issue.
In the case of a large combustion apparatus, the large static pressure given by the combustion fan provides advantages such that the combustion gas and air can be easily controlled in flow. The burner is high in the degree of freedom of layout, and noise can be controlled easily. So, noise control is not difficult, and since the combustion chamber can be large, slow combustion as a means for decreasing NO.sub.x allows one to easily achieve perfect combustion. On the contrary, in the case of a small combustion apparatus, especially a small combustion apparatus for burning a large quantity, these advantages are not available and it is difficult to take measures for decreasing NO.sub.x, as compared to large combustion apparatuses.